In the beginning when grass wasn't green, Eagle was sitting by the pool. Eagle considered green to be superior to other colors because it was his favorite.
After flying to Bear's house, Eagle tried to convince Bear that everything in the world needed to be green. Bear disagreed, believing that the world should have more colors than just green. Eventually, Eagle admitted that Bear was right.
Everything needs to be green here because it is my favorite color.
Not everything! There should be more color than that in the world.
Eagle learned that not everything can be what you want it to be and he accepted that he was wrong. From that point forward, grass was green but the world was full of other colors too.